It's a large crowd for a crumbling lava tube two kilometres down an gravel road in Iceland, but everyone's here for the same reason: to see the cave purportedly used in the hit show, Game of Thrones.

Fans have an insatiable appetite for their favourite shows and television tourism is on the rise. Albuquerque, New Mexico, has experienced an influx of visitors in the wake of the Breaking Bad finale, while Highclere Castle in England, best known to viewers as TV's Downton Abbey, is packed on open days thanks to its celebrity status.

Iceland is no different. Tourism has increased 20 per cent year on year recently, in part due to its starring role in the HBO series Game of Thrones.

In the show, Iceland's dramatic frozen landscapes double as the fictitious world George R. R. Martin penned "beyond the wall", a brutal, unforgiving environment on the edge of civilisation filled with supernatural whitewalkers and savage wildlings.

While Iceland remains an eye-wateringly expensive destination for visitors, it's an affordable location for filmmakers, thanks to the country's tax incentive programme.

In a number of behind-the-scenes featurettes, the executive producers of Game of Thrones have clearly expressed their preference for spending the show's budget on dramatic locations as opposed to visual effects, and with a combined audience of 13.6 million people in America alone, it seems they've got the formula right.

Iceland's tourism industry has benefited with the country's dramatic landscapes showcased to the world.

Parts of season two were shot in the south-east of the country, around the tongue-twistingly-named Svinafellsjökull, a glacial "tongue" of the enormous Vatnajökull glacier which covers eight per cent of the country's landmass, while season three was filmed in the north around Lake Myvatn.

By chance, my visit to Iceland in August this year coincided with the filming of season four on the outskirts of Reykjavik in Thingvellir National Park.

The town (and internet) buzzed with gossip; Aidan Gillen (Littlefinger) and Peter Dinklage (Tyrion Lannister) had supposedly been spotted in the Big Lebowski bar, while Gwendoline Christie (Brienne of Tarth) won local favour by stopping for photos.

Things reached fever pitch however, when this achingly dull YouTube video hit more than 35,000 views after the driver unwittingly drove through the Game of Thrones set, filming two characters in full costume at the 5.45 minute mark (one with a very un-Westeros-like fag hanging from his mouth).

However, actor Kit Harrington, who plays Jon Snow, was nowhere to be seen - and if I couldn't orchestrate a run-in with the man himself, there was just one Game of Thrones location I wanted to see: Jon Snow's cave.

The cave was the location of the infamous scene where Jon Snow (who had for most of the series been a bit of a wet blanket) finally proved his prowess with a series of strategically placed kisses, firmly disproving Ygritte's catchphrase: "You know nothing, Jon Snow."

The exterior of this adults-only sequence, where Ygritte playfully steals Jon's sword, was shot in Myvatn on the Dimmuborgir lava fields.

With a little movie magic, the scene switches to another location nearby, Grjotagja, a lava cave with a geothermal spring at the bottom, where Ygritte calls Jon out as a chicken and runs inside.

When we drive up to the cave, it's not quite what we expected. There's a small crowd hovering round the entrance, put off by the signs warning of recent rock collapses.

Inside, more foolhardy fans take photos and test the acoustics by shouting. It is not in anyway the romantic place I imagined.

Throwing caution to the wind and ignoring the crowds, we enter, scrambling down boulders to the pools, where shards of soft afternoon light illuminate chest-deep clear water.

Wasps of steam play on the surface, and when I crouch and touch the surface, the warm 46-degree water tempts me to jump in (even if the stench of sulphur doesn't).

It's a sublime sight, but my companion and I agree: it's not Jon Snow's cave. A repeated viewing of the scene back at our hotel, along with a more thorough Google search reveals that the entrance of Grjotagja was possibly used for filming, but the cave interior was constructed on a soundstage and the scene shot in Belfast.

Are we disappointed? Not at all. While the magnificent scenery in Game of Thrones was the catalyst for us visiting Iceland, the country delivered so much more than revealed in the series.

We had been awed by the dramatic volcanic wilderness, overwhelmed by encounters with humpback whales and puffins and welcomed with an unforced friendliness by locals.